> restart;
> with(plots):
>
> constraint1:=plot3d([t,-3/2*t,s], s=-300..900, t=-10..10, axes=boxed):
> quadraticform:=plot3d(x^2+4*x*y+y^2, x=-10..10, y=-15..15, axes=boxed):
> display(constraint1,quadraticform);
>
> constraint2:=plot3d([t,3/2*t,s], s=-300..900, t=-10..10, axes=boxed, orientation=[185,85]):
> display(constraint2,quadraticform);
>
>